Expression of lamin A in colorectal cancer cells can induce epithelial-mesenchymal transition


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Clare Foster1, Naomi Willis1, Joanne Robinson1, Thomas Cox1, Danielle Battle1, Daniel Swan2, Robert Wilson3, Christopher Hutchison1
1Durham University, Durham, United Kingdom,2Newcastle University, Newcastle, United Kingdom,3James Cook University Hospital, Middlesborough, United Kingdom

Background

Lamins are type V intermediate filament proteins found at the nuclear envelope. We have previously shown that expression of lamin A in colorectal cancer (CRC) tumours is correlated with very poor prognosis (1). Furthermore, expression of lamin A in CRC cell lines promotes greatly increased cell motility (1). The aim of study is to identify proteins that promote cell motility in response to lamin A expression.

Method

Cell fractions containing nucleo- and cytoskeletons (N/CSKs) were isolated from CRC cells containing either GFP-laminA (SW480/lamA) or GFP (SW480/cntl). The cell fractions were used in 2D DIGE (Difference Gel Electrophoresis) analysis to quantify differences in protein abundance. Proteins of interest were identified using MALDI-TOF mass spectrometry. 

Genome-wide Affymetrix microarray analysis of SW480/cntl and SW480/lamA cell lines was performed. Interaction networks were produced by Ingenuity Pathway Analysis (IPA), which showed known literature-curated interactions. 

Results

The proteomic and genomic data revealed that epithelial markers such as E-cadherin were down-regulated and mesenchymal markers such as vimentin were up-regulated in cells expressing GFP-lamin A. This suggests that the cells are undergoing an epithelial-mesenchymal transition (EMT), a process known to be involved in cancer progression and metastasis. 

The most highly significant network produced by IPA clustered together molecules linked to cancer, cellular movement and cellular growth and proliferation. 

A-type lamins are known to modulate downstream effects of TGF-?1 signalling (2). As TGF-? is an inducer of EMT, we decided to investigate the effect of lamin A expression on TGF-? target genes. si-RNA knockdown of lamin A in CRC cells led to a reduction in the gene expression of TGM2, TGF-?I, SNAI2 and ZEB1 and reduced cell motility.

Conclusion

Our data suggests that expression of lamin A in CRC cells increases the risk of death from cancer through EMT which leads to increased cell invasiveness.